Vaulted fluid storage systems

ABSTRACT

The present invention provides visual inspection and physical access into the space of a fluid containment system consisting of an inner storage container or vessel, and an outer, reinforced precast structure, or vault, having a top cover. Visual inspection ports and physical access assemblies, with easily removable covers, are cast into the vault top corners for direct, or remote viewing, such as with a periscope or video camera device, of the exterior surfaces of the inner storage container; the interior surfaces of the outer, vaulted structure; and the space between the two structures. Sufficient physical access and physical maneuverability is provided by the visual inspection port assemblies, and corresponding visual inspection chambers directly below each port assembly, that proactive inspection to verify primary vessel integrity and removal of fluids from the interior space between the two containers can be achieved without personnel entry or removal of the vault top.

FIELD OF THE INVENTION

[0001] The present invention relates to fluid storage and containment assemblies and in particular, to above ground, below grade, and at-grade, multi-sectional containment systems comprising a primary, inner storage vessel; an interstitial, secondary containment space, and an outer, reinforced, secondary containment structure.

[0002] More particularly, there is provided multiple access means in the top of the reinforced, secondary containment structure to view the integrity of the primary and secondary storage containers, the interstitial secondary containment space between the two containers; and to provide for sufficient inspection and physical access into the interstitial space so as to provide for removal of liquids from the interstitial space without having to enter the space or remove the reinforced secondary containment structure.

BACKGROUND OF THE INVENTION

[0003] A variety of above ground, below grade, and at-grade storage systems are provided in which a primary vessel, that stores environmentally hazardous and/or corrosive fluids, is surrounded by a reinforced, precast, factory poured, secondary containment structure, or vault.

[0004] The above ground, below grade, and at-grade storage systems are generally provided for storing, dispensing and transferring environmentally hazardous fluids such as petroleum products, chemicals, pressurized gases, solvents, acidic solutions, etc. The primary vessels are generally constructed of steel and manufactured to Underwriters Laboratories (UL) manufacturing standards such as the UL-142 tank manufacturing standard, “Steel Aboveground Tanks for Flammable and Combustible Liquids”, for ambient temperature vessels (non-pressurized), but may include pressure vessels. Usually, the primary vessels are steel, but may include any primary vessel material compatible with the stored fluid.

[0005] The above ground precast vaulted storage system are tested to the UL-2085 “Fire Protected Standard for Insulated Secondary Containment Aboveground Storage Tanks For Flammable and Combustible Liquids” performance standard which requires a minimum two-hour fire test, hose stream test, ballistic resistance test, and a heavy vehicle impact simulation test. The below grade and at-grade fully assembled systems are tested under the UL-2245 Standard for Below Grade and At-Grade Vaulted Storage Systems.

[0006] With respect to prior above ground containment systems and structures, some systems utilize the primary steel vessel as the inner form for the casting of the monolithically poured outer, reinforced, precast container directly under, around, and over the inner vessel, leaving a one inch (1″) diameter steel drop tube as the only physical monitoring and access means after the structure is poured. Visual inspection, with this above ground prior design, is solely relegated to the exterior of the assembled system for signs of external leakage. Physical access is obviated and impossible.

[0007] In other above ground prior systems, the primary vessel is surrounded by another outer container, usually steel, that forms a secondary containment cavity that is, subsequently filled with a porous, non-reinforced cementious mix that allows for migration of liquids to a specific location within the filled cavity, even after curing of the mix to a typical density of 3000 psi. Monitoring of the primary and secondary internal containment components of these prior art designs are, again, limited to non-visual physical monitoring of the secondary containment space by means of a steel pipe drop tube assembly manufactured into the filled cavity.

[0008] In yet other above ground prior system as disclosed in U.S. Pat. Nos. 5,249,698, 5,299,709 and 5,285,914 which are herein incorporated by reference, the outer, reinforced, precast, factory poured, secondary containment structure includes a removable top, so as to inspect the condition of the primary vessel, or to gain physical access to the primary vessel for inspection, repair, or replacement of the primary vessel.

[0009] Although prior above ground systems have utilized similar primary tank, interstitial space, and two-part secondary containment designs; visual inspection of, or physical access to, the primary vessel and interstitial space is possible only by the lifting of a heavy precast top section or lid, or combined tank and lid assembly manufactured as an integral unit.

[0010] Insofar as the fittings of the primary vessel are generally grouted, or otherwise, sealed into the top of the secondary containment structure to ensure fire protection and/or weather tightness; and further, due to the generally heavy weight of the reinforced, precast lid assembly, whether flat or cylindrical in design, visual inspection of the primary vessel, for the cited above ground prior art with two-part construction, becomes a function of the significant cost of the required lifting equipment (cranes, forklifts, etc.); physical access to the site; and/or the significant labor and expense required to disassemble and reassemble the precast, two-part constructed vault before and after the desired inspection.

[0011] Weekly or monthly tank inspections of the primary vessel in the above ground prior art cited above are, generally, out of the question due to the time, expense, and specialized lifting equipment required in attaining the required access for the desired inspections. Visual inspections of the primary vessels in these systems, although physically possible with the two-part construction design, are simply not practical therefore, simply not done.

[0012] In U.S. Pat. No. 5,285,914, it is stated that leakage in the space between the primary tank and the secondary container may be detected through the use of a drop stick or by “visual inspection” of the base interior through a standard two-inch (2″) diameter standpipe and drop tube assembly manufactured into the system. Although the standpipe does create a physical space into the containment area, it is impossible to see any significant distance into, or through, a long two-inch diameter standpipe, even in the best of circumstances during daylight hours, let alone when it is to be used as a single “visual inspection” port into the dark recesses of a secondary containment space that, at a minimum, would have a base interior distance of three feet, and up to eight feet below and away from the bottom of the standpipe in the vault top. Secondly, should one be able to somehow see the refection of liquid in the base interior are (2-inch diameter area) directly below the standpipe, there is, once again, no physical access to the secondary containment space short of removing the heavy precast top.

[0013] Additionally, one other attempt was made in above ground prior art to incorporate a visual inspection apparatus into the overall design by Cruver et al (U.S. Pat. No. 5,249,698). This apparatus was a set-through eyeglass cast into, or otherwise inserted into, the bottom of the interior of the vault at the point where a drainage channel, positioned down through the center of the vault bottom, deposited effluent or spilled liquids directly in front of the see-through apparatus, which would then show a yellowish color when viewed from the exterior, indicating that a spill had occurred internally. Unfortunately, industry standards and fire code regulations consider openings in the bottom or sides of the precast vault bottom as a potential breach of the secondary containment structure. This design represents a reactive design approach and precludes physical access to the space without removing the heavy precast top section of the containment system.

[0014] The current invention, however, invites and promotes daily, weekly, or monthly visual inspections of the primary vessel, and the secondary containment spaces and structures, by providing quick and easy visual and physical access to the internal components and surfaces without having to undergo the time, labor, and expense of having to first remove the heavy precast top section of the secondary containment structure.

[0015] For below grade and at-grade designs such as disclosed in U.S. Pat. No. 4,978,249 to Killman has generally provided for visual or physical access into the secondary space around primary vessel by means of a traditional manway access with a removable cover.

[0016] As the entry into the secondary space of a below grade or at-grade storage system is considered hazardous due to the possible presence of vapors or hazardous fumes, “Confined Space Entry” procedures as outlined and published by OSHA (Occupational Safety & Health Administration) usually apply. These procedures involve written permitting for entry by qualified and authorized personnel; specialized breathing equipment; specialized gas-monitoring equipment; specialized harnesses and retrieval equipment; and the required presence of two or more persons posted outside the structure throughout the entirety of the entry and inspection process.

[0017] The current alternatives in prior systems for monitoring of the primary vessel and secondary containment spaces and/or structures are, historically, more reactive in design; that is, the product release must occur first to activate standard electronic leak-detection sensors and monitoring equipment.

[0018] The simplest and most common method of reactive monitoring is the use of a 2-inch (2″) diameter steel drop tube and dipstick assembly wherein a wooden stick is manually inserted like a dipstick into a steel drop tube that has been manufactured into the secondary containment space. The wooden stick is then retrieved and examined for indications of fluids. A paste can be applied to the bottom of the stick before inserting into the drop tube to help determine whether the wetted area contains any petroleum product, or is simply accumulated condensation inside the chamber. Current practice is to rely on a human smelling the dipstick to determine the presence of petroleum based or otherwise hazardous liquids.

[0019] The other most prevalent method of reactive monitoring is that of inserting an electronic monitoring probe into a drop tube assembly manufactured into the secondary containment space. Upon contact with liquid in the secondary containment space, the probe sends a signal to a visual (light) or an audible alarm (bell) signaling that a liquid has been detected. After an alarm, the electronic monitoring system is generally designed to shut down the storage system, including any dispensers or pumps that may be included on the system, until such time as an authorized representative of the monitoring system can examine the exact cause of the alarm, verify the absence or presence of effluent, and reset the monitoring system and alarms. The frequent down time resulting from false alarming of the system due to condensation, and the subsequent waiting for qualified service personnel to arrive, inspect, and complete this servicing procedures, is generally considered to be an expensive and timely aggravation that simply must be endured when storing environmentally hazardous fluids.

[0020] Direct visual inspections of above ground systems has been largely limited to the exterior surfaces of the assembled system. For below grade and at-grade systems, direct visual inspections generally require physical entry into hazardous confined spaces, and are, therefore, generally, not performed on a regular basis due to the specialized procedures, specialized equipment, and high health and safety risks.

[0021] Remedies flowing from these reactive, traditional methods of internal physical monitoring, or of relying only on external visual inspections, are considerably more complicated and expensive, as the integrity of the system must, by necessity, have already failed before the monitoring system devise is activated.

[0022] With a two-part, precast vault construction, the invention, like prior systems, does allow for thorough maintenance and/or repair of internal components and protective coatings by removing the vault top section of the secondary containment structure. An advantage of this invention over prior art with similar two-part precast vault construction, however, is that major preventative maintenance or repair of the primary vessel or secondary containment components requiring removal of the vault top, can be readily assessed and scheduled at the appropriate intervals, or determined not to be necessary at all, without having to first remove the heavy precast secondary structure lid and dismantle the integral containment system in order to make a maintenance related assessment.

[0023] The invention, thereby, eliminates unnecessary operational expenses inherent in the prior art designs that require removal of the heavy precast top for inspection purposes, and increases the integrity and ultimate service life of the assembled system by providing the appropriate means and access to proactively inspect, maintain, repair, or replace the various primary containment components and/or protective coatings of the containment system in a timely and economically desirable fashion.

SUMMARY OF THE INVENTION

[0024] According to the present invention, there is provided a fluid storage system comprising:

[0025] 1. an outer, reinforced pre-cast secondary container and structure having a bottom wall and a plurality of side walls which project from the bottom wall to define a cavity;

[0026] 2. an inner, primary vessel and container inside of said open cavity, said inner container capable of holding fluids and being spaced from the outer container, and,

[0027] 3. a reinforced pre-cast, secondary containment cover over the cavity supported by the side walls of the secondary structure.

[0028] The improvement in the system comprises that the reinforced, secondary containment cover having at least one, preferably two to four corner mounted visual inspection and at least one physical access port to provide viewing and physical access into the space between the primary vessel and interior walls of the reinforce secondary structure.

[0029] Also, the visual inspection port covers are bolt down, water-proof, weather-tight, and fire resistant to 2,000 degrees as measured by a fire exposure lasting two or more hours (UL-2085 Standard). The easily removable port covers also contain means for physical access and/or viewing of the cavity without removing the precast covers depending on the geometry and size of the visual inspection ports.

[0030] Advantageously, the visual inspection port covers may include a manual or electronic periscope, or other remote video or viewing means for visually assessing the real time condition of the surfaces and protective coatings of the inner and outer containers, as well as the secondary containment space between the containers for internal leakage or spillage.

[0031] Preferably, a natural or artificial light source may be introduced within the cavity of the system, or in association with the visual inspection capability without removing the precast secondary container cover.

[0032] It is yet therefore, a general object of the invention to provide a fluid containment system comprising an outer, reinforced, secondary containment structure; an interstitial secondary containment space; and an inner storage vessel, which can be visually inspected and viewed without removal of the precast, secondary containment cover.

[0033] It is another object of the invention to provide sufficient physical access into the space between an inner storage vessel and an outer, secondary containment structure so as to be able to remove fluids from the interior interstitial space without physical entry into the space, and without removal of the precast secondary containment cover.

[0034] It is another object of the invention to provide sufficient physical access into the space between an inner storage vessel and an outer, secondary containment structure so as to be able to remove fluids from the interior interstitial space or perform maintenance and/or repair operations with physical entry into the space, and without removal of the precast secondary containment cover.

[0035] It is another object of the invention to provide means for remotely viewing the integrity of the surfaces and coatings of the inner and outer containers, as well as the space between the inner storage vessel and outer, reinforced, secondary containment structure without removing the precast, secondary containment cover.

[0036] It is another object of the invention to provide means for remotely sensing and sampling the atmosphere contained within the interstitial space and sealed by the said containment system using electric and electro-optic means.

[0037] It is further an object of the invention to provide means for viewing the interior of above ground, below grade, or at-grade liquid storage vaults.

[0038] These and other objects and advantages of the invention will become more apparent from the foregoing description of preferred embodiments and from the drawings, herein:

BRIEF DESCRIPTION OF THE DRAWINGS

[0039]FIG. 1 is a perspective view shown in partial cutaway of the assembled above ground fluid containment vessel of the present invention.

[0040]FIG. 2 is cross sectional view of FIG. 1.

[0041]FIG. 2a is a cross sectional view of the vault joint assembly of FIG. 2.

[0042]FIG. 2b is a cross section view of the primary tank riser and vault top configuration of FIG. 2.

[0043]FIG. 2c is a perspective view of the visual inspection port assembly of FIG. 2.

[0044]FIG. 3 is a top view of the vault top assembly of FIG. 1.

[0045]FIG. 3a is a top view of the primary tank manway of FIG. 3.

[0046]FIG. 3b is a cross sectional view of the primary tank manway of FIG. 3.

[0047]FIG. 4 is a top view of the vault bottom of FIG. 1.

[0048]FIG. 5 is a cross sectional view of the manual inspection mirror with integral artificial light source.

[0049]FIG. 6 is a perspective view shown in partial cutaway of the below grade and at-grade fluid containment vessel of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE PRESENT INVENTION

[0050]FIG. 1 depicts an isometric drawing in partial cutaway of the assembled above ground fluid storage system 10 components comprising the present invention. The assembly 10 generally consists of an above ground (UL-142), rectangular shaped, primary containment vessel or tank 16 encased within a reinforced, factory poured, precast, concrete vault bottom section 14 with a removable vault top section 20.

[0051] For the construction shown, the assembled invention 10 provides for two-hour fire wall protection at 2000 degrees F.; ballistic protection; and high impact protection (UL 2085 Fire Protected Standard for Insulated Above Ground Storage Tanks) as mandated by NFPA 30 and 30A regulatory code (National Fire Prevention Association); UFC Standard A-11, F-1 regulatory code (Uniform Fire Code); and BOCA regulatory code (Building Officials Code Administration).

[0052] For the construction shown, the primary tank 26 is fabricated using a single wall steel vessel and is rectangular in shape; although it could be constructed of any material impervious to and compatible with the stored liquid, and capable of sustaining the physical loading requirements as mandated by the Underwriters Laboratories performance rating. The shape of the primary tank 16 could be cylindrical, round, square, oblong, or rectangular. The primary tank 16 wall construction may be of one or more layers for increased containment assurance. The primary tank 16 may also be divided into two or more compartments with single or double bulkheads separating the various compartments. Generally, the primary tank 16 is an ambient temperature vessel (non-pressurized), but it may also be a pressure vessel. The primary tank 16 is generally coated with a rust preventative coating 43 for corrosion protection, and may be additionally coated with two-part epoxy coating for enhanced corrosion protection.

[0053] Further, for the construction shown, the primary tank 16 is chamfered on all four corners to create a triangular shaped, visual inspection and physical access chamber 19 between the exterior, chamfered corners 18 of the primary tank 16 and each of the corresponding interior corners of the vault bottom section 14 and extending upward from the interior floor of the vault bottom section 14 to the interior surface of the vault top 20. The primary tank 16 may employ from two to four corner chambers, with at least one corresponding visual inspection and physical access chambers 18 being formed between the primary tank 16 chamfered corners 18 and the vault bottom 14 corners and vault top sections 20, as described. Quick and easy access into the visual inspection chamber 19 is facilitated by means of corner mounted visual inspection port assemblies 35 as shown or physical access manways which are cast into the vault top section 20.

[0054] The reinforced, factory poured, precast vault consisting of a monolithically poured bottom section 14 and the vault top section 20, are cast and manufactured independently of the primary containment tank 16 fabrication. Openings in the vault top 20 are pre-engineered to coincide with the primary vessel 16 fittings that project upward through the vault top 20 during the assembly of the component structures into the assembled invention 10.

[0055] For the construction shown, the vault top 20 is flat, but may also be of “clamshell” design for extended height, wherein the monolithically poured side walls protrude downward from the vault top 20 forming a “roofed” upper cavity which is then mated with the vault bottom section 14.

[0056] The vault bottom section 14 may incorporate a protective coating 21 on the interior floor and wall surfaces for enhanced secondary containment protection. Generally, a petroleum resistant, two-part epoxy coating is applied to the vault bottom 14 surfaces to a thickness of 5-10 mils by means of an airless sprayer. Optional polyurea based coatings of 35-45 mil thickness may be sprayer applied to the vault bottom 14 interior surfaces that comprise the secondary containment structure to achieve even greater enhanced secondary containment protection. Optional monolithic lining materials such as polyethylene plastic preformed sheeting suitable for petroleum and chemical containment, and polystyrene insulation materials may be used in place of, or in combination with applied protective coatings for enhanced secondary containment protection on the interior surfaces of the vault bottom section 14 and sidewalls. The primary insulation feature of the invention is about 1″ to 2″ of interstitial air space that comprises the secondary containment space 17 between the primary tank 16 and the vault bottom section 14. This interstitial airspace may be dimensionally changed to accommodate either visual inspection ports or physical access manways depending on the desired functionality. Additionally, the interstitial airspace may be used as a cavity to introduce dessicant or super-absorbent materials to aid in the absorption of effluent and fluids leaked from the primary containment vessel.

[0057] The current invention can prove auxiliary warm/cool air insulation/cooling options if the assembled system 10 is to be installed in a geographic area where thermal insulation and/or regulation of internal condensation are of utmost importance. The assembled system 10 utilizes a remote, full time ventilation fan that connects through underground or above ground vent piping to the cast-in input ventilation riser 31 on the vault top 20 of the assembled invention 10. By forcing in fresh air through a ventilation pipe riser 31, that is then either cooled or heated at the remote fan site to properly counteract the existing atmospheric conditions, the assembled invention 10 can be maintained at a desired internal temperature that will greatly reduce or eliminate internal condensation and, accordingly, potential corrosion of the primary tank 16. The fresh air that is pushed into, around, and through the interstitial space 17 is exhausted through a return ventilation riser 32, and return piping (not shown) to a remote ventilation riser (not shown) 25′ away from the assembled invention 10 and is at least 12′ above grade.

[0058] Advantageously, in addition to providing remote, thermal air insulation or cooling properties to the assembled invention 10, the optional forced-air ventilation system, in the event of an external fire, significantly reduces the possibility of internal combustion within the interstitial space 17 when operated at a minimum flow rate of 150 cfm (cubic feet per minute).

[0059] As seen in FIG. 4 the vault bottom section 14 employs an interior drainage channel 12 and sump 13 configuration that passively accepts moisture and liquids that may accumulate on the floor of the vault bottom section 14 and directs, by means of gravity, such moisture and/or liquid accumulations to the designated sump 13 areas. Easy removal of liquids from the interior cavity of the assembly can be achieved by means of an external pump or vacuum hose lowered through the opened visual inspection port 35 assembly mounted on the corner of the vault top section 20 directly over the sump 13 locations at the corners of the floor of the vault bottom 14.

[0060] The vault bottom section 14 employs two or more monolithically poured vault feet 22 on the exterior bottom surface of the vault bottom section 14 for direct load bearing of the dynamic weight of the primary tank 16, and for visual inspection capability under the exterior of the vault bottom 14 for the assembled invention 10. Feet or channels located on the primary containment vessel are positioned to lie directly above the precast feet of the precast secondary structure to mitigate dynamic loads and reduce and/or eliminate stress cracking to the precast secondary containment structure.

[0061] The bottom vault section 14 further utilizes an inert rubber gasket material 23 directly under the primary tank feet 24, and directly over the vault exterior feet 22 to prevent galvanic action between the primary tank feet 24 and the interior precast surfaces of the vault bottom section 14.

[0062] This direct, vertical alignment of the primary tank feet 24 and exterior vault feet 22 of the invention further eliminates dynamic load stress fractures in the precast vault bottom 14 that have been documented elsewhere with the U.S. Pat. No. 4,826,644 (Lindquist et al) as a result of casting the precast vault directly around the flat bottom primary tank (no tank feet), resulting in continuous increases and decreases in load pressures on the unsupported precast sections of the vault bottom between the exterior load bearing vault feet.

[0063] The exterior surfaces of the outer, reinforced vault top 20 and vault bottom sections 14 can be provided with a two-part epoxy or polymer based coating 45 for added weather resistance. Indentations 11 are cast into the center and corners of the upper exterior vault walls of the vault bottom 14 for placement and added protection of industry standard product and warning signs. The exterior of the vault top 20 is crowned to facilitate water run-off. Cast-in, lifting pins 38 are recessed into exterior surface of the vault top 20 and covered with an elastomeric epoxy material 34 that is easily removed should future access to the lifting pins be desired for removal of the vault top 20. The exterior top of the primary tank 16 can also be configured with at least two non-penetrating, female threaded fittings 15 that accommodate a removable, male threaded lifting device for the future lifting and/or removal of the primary tank, if desired.

[0064] Generally, the secondary containment, or interstitial space 17 between the primary vessel 16 and the outer, secondary containment vault bottom section 14 and vault top section 20, is designed to provide a minimum of 110% secondary containment of the overall primary vessel 16 capacity. For the construction shown, the 110% secondary containment capacity is achieved below the vault joint 25, and this is the preferred embodiment. However 110% secondary containment of the primary vessel 16 may be achieved, as in the aforementioned “clamshell” design, by incorporating the sealed vault joint 25 and portions of, or all of the vault top section 20 walls into the secondary containment design.

[0065] The 110% secondary containment capacity of the interstitial space 17 provides total containment of any potential product release. Although 110% secondary containment is the standard for the invention, the amount of secondary containment capacity can be adjusted upward or downward to suit the requirements of specific containment requirements by modifying the size of the vault bottom 14 to the capacity of the primary tank 16.

[0066] For the construction shown in FIG. 1, the vault joint 25 between the vault bottom section 14 and the vault top section 20, may consist of a tongue and groove configuration 25 for enhanced fit and sealing of the two-piece construction. Various larger or other configured versions of the invention may employ a standard shiplap joint, or otherwise stepped, configuration without sacrificing any fit, sealing, or fire resistant properties for the assembled invention 10.

[0067]FIG. 2a is a cross section view of the vault joint configuration 25. A weather-tight, petroleum resistant seal of the vault joint 25 components for example can be achieved by means of a butyl rubber primer 27 applied to the precast surfaces comprising the vault joint 25 configuration. Next, a seamless, moisture and petroleum resistant, gasket material 28 is secured continuously on the outer, flat surface of the vault joint 25 configuration of the vault bottom section 14. Additionally, the vault joint 25 assembly incorporates an aluminum-silicon, ceramic, refractory, and gasket material 29 on the inner, flat surface of the vault bottom section 14. This inner gasket material provides for two-hour fire protection for the primary tank 16 at 2,000 degrees F.

[0068] For the construction shown in FIG. 1, the vault joint 25 sealant material 28 can be compressed down to a minimum of fifty-percent of the original size by the weight of the reinforced, vault top 20 upon assembly of the two-piece construction. This is a preferred and standard method of weather-tight sealing of the vault top section 20 to the vault bottom section 14. However, an optional, mechanical means of applying additional, single, or multiple compression forces to the vault joint 25 configuration and sealant material 28 can be achieved by means of a cast-in, threaded rod (not shown) into the vault bottom section 14 at the vault joint 25, that projects upward and through a corresponding, pre-engineered opening in the vault top section 20 for fastening, and compressing to the desired force. The top of the threaded rod and fastening assembly is, typically, recessed into the vault top section 20, and filled with an elastomeric, epoxy sealant material to a level flush with the top surface of the vault top section 20.

[0069]FIG. 1 also shows a variety of primary tank fittings 36 that project upward form the top of the primary tank 16 cavity and through the reinforced, pre-engineered openings in the vault top section 20. FIG. 2b shows a cross section view of how the reinforced, pre-engineered openings in the vault top section 20 are sufficiently sized to each of the tank fittings so as to allow for the introduction of insulation material 29 for fire resistance; and a combination of grout material 33, and an elastomeric, epoxy material 34 for weather-tight sealing of the primary tank fittings 36 to the vault top section 20. In addition to providing fire resistant, weather-tight seals for the tank fittings, the assembly sequence and sealing of the primary tank fittings 36 can provide physical stability of the primary tank 16 inside the cavity of the vault bottom section 14, and provide additional stability to the vault top section 20, when used in combination with tongue and groove 25, shiplap, or stepped joint configuration.

[0070] A typical grouping of primary tank fittings 36 which can be used is shown in FIG. 1 for a primary tank 16 with a single product containment configuration. As noted, primary tank 16 shape and size configurations may vary within the assembly 10 to meet multiple product containment needs within the assembled invention 10. The size and number of primary tank fittings 36 may vary in accordance with the specified containment requirements demanded of the primary tank 16.

[0071] The penetrating, primary tank fittings 36 are, generally, threaded on the top end; project about four to six inches through the vault top section 20; receive externally mounted, counter threaded, industry standard accessories (not shown) for the proper operation of the assembled invention 10; originate at the top of the primary tank 16 top surface; are integrally welded to the top surface of the primary tank 16; and lastly, open directly into the primary tank 16 inner cavity through the bottom opening inside each of the respective fittings.

[0072] In FIG. 1, primary tank fitting 37 is for the external mounting of a tank product level gauge that indicates the level fluid contained in the primary tank 16 cavity. Primary tank fitting 39 is for an extended atmospheric ventilation riser pipe and vent cap assembly properly sized and suited to the fluid contained in the primary tank 16. Primary tank fitting 40 is for an industry standard emergency vent fitting, sized and suited to the primary tank 16 capacity, wherein the emergency venting of vapors inside the primary tank 16 cavity are released in a manner consistent with safety standards for the industry. Primary tank fitting 41 is for the installation of any number of industry standard electronic detection devices or alarms within the primary tank 16 cavity. Primary tank fitting 42 is an extra fitting for undetermined and/or miscellaneous access into the primary tank 16 cavity. Primary tank fitting 43 is a manway with a bolt down, gasketed, weathertight, and removable cover that permits authorized personnel access into the primary tank 16 cavity for service, repair, or maintenance operations. Although shown in the form of construction in FIG. 1, generally, industry standards require a primary tank manway 43 only on primary tank 16 capacities of 4,000 gallons or more.

[0073] As drawn in FIG. 2, there are three additional penetrating, primary tank fittings 36 that are housed within the integral, primary tank 16 overspill container 44. The first is primary tank fitting 45 that serves as the fill port for the primary tank 16. As such, primary tank fitting 45 typically provides access for the installation of an industry standard drop tube and fill limiter assembly, often with a specialized adapter and cap assembly for advantageous filling and security. Secondly, primary tank fitting 46, is for an industry standard vapor recovery adapter and cap for flammable fluids, or simply serves as an extra fitting inside the lockable overspill container 44. The last primary tank 16 fitting is a manually operating drain mechanism 47 that allows spilled product within the overspill container 44, to be released back into the primary tank 16 cavity.

[0074] Advantageously, the use of a rectangular primary tank 16 allows for more economy and versatility in the placement of the primary tank fittings 36, as the placement of such fittings is not restricted to the center line of the primary tank 16, as is the case with a fluid storage system that utilizes a cylindrical primary tank. Primary tank fittings 36 and the overspill container assembly 44 can be positioned virtually anywhere on the rectangular top of the primary tank 16. When used in conjunction with dual tank configurations, the rectangular tank 16 design further allows for bulkhead placements either horizontally across the width of the top of the primary tank 16, or in a linear fashion dividing the length of the rectangular tank 16. With placement of two overspill containers 44 on either the side of the bulkhead dividers within the primary tank 16 single stair and/or platform access may be utilized to fill and service both compartments created by either of the bulkhead configurations. Cylindrical tank based systems can only be divided with a bulkhead across the width of the tank, and the overspill containers at the point of fill tend to be much higher, and usually require dual access points when utilizing a compartmentalized tank.

[0075] The non-penetrating, overspill container 44 is integrally welded to the top of the primary tank 16, but does not penetrate into the cavity of the primary tank 16. Equipped with a hinged 44 b lid 44 d assembly with a handle 44 a and locking tab 44 c mechanism, the overspill container 44 projects upward through the vault top section 20 to a height of about six to nine inches above the top of the vault top section 20, and serves as a secondary containment device at the point of fill 45 for the primary tank 16. The assembly and sealing of the overspill container 44 into the vault top 20 is consistent with the procedures described above for the penetrating primary tanks 16 fittings.

[0076]FIG. 1, further shows a variety of integral, vault top 20 fittings that are directly cast into the vault top section 20, but do not penetrate downward into the primary tank 16 inner cavity. Of this grouping, riser pipe 48 is cast into the vault top section 20 so as to have one end flush with the underside surface of the vault top 20 section, and with the other threaded-end revealed four to six inches above the uppermost surface of the vault top section 20. This threaded riser pipe 48, serves as the external connection for an industry standard emergency vent fitting that permits potential vapor pressure to escape from the interstitial space 17, in the event of spilled liquid in the interstitial space 17, and an external fire to the assembled invention 10. Integral riser pipe 48 is sized to match the size of the primary tank 16 emergency vent riser pipe 40 which is based on the wetted area of the inner cavity of the primary tank 16.

[0077] Additional fittings, such as additional access assemblies not show in FIG. 1, may be cast into the vault top section 20 provided adequate reinforcement, fire protection gasket 29 placements, and weather resistant sealing procedures are consistent with the construction and procedures herein described.

[0078] The visual inspection port assemblies 35, mounted on the top corners of the vault top section 20 and shown in FIG. 1, may be integrally cast into the vault top section 20 (FIG. 2). The visual inspection port assembles 35 consist of a bottom cast-in rain skirt 35 a and rim 35 b assembly, with a bolt down 35 c, gasket 35 d, weather-tight, and removable manway cover 35 e. The removable manway cover 35 e may include additional fittings or openings 35 f, for the facilitation of direct or remote visual, or physical monitoring and/or access into the visual inspection chamber 19 positioned directly below each of the visual inspection port 35 assemblies.

[0079] For above ground placement of the assembled invention 10, the removable manway cover 35 e of the visual inspection port assembly 35 includes a layer of aluminum-silicon ceramic, refractory insulation 35 g securely attached to the underside of the removable manway cover 35 e by means of an epoxy adhesive 35 h material, and one or more threaded rods 35 k, washer 35 m, and nut 35 p assembles as shown in FIG. 2c. One end of the threaded rod 35 k is welded to the underside of the removable manway cover 35 e, and services as a mechanical compression devise for securing the aluminum-silicon, ceramic refractory insulation 35 g. The visual inspection port 35, for above ground placement provides two-hour fire protection for the primary tank 16 at 2,000 degrees F. All of the metal components of the visual inspection port assemblies 35, are typically sandblasted, primed, and two-part, epoxy coated for long term corrosion protection. The size and shape of the visual inspection ports 35, may be modified to meet the visual and physical access requirements of any individual, or groups of, the assembled invention 10.

[0080] For enhanced, direct visual inspection through the opened visual inspection ports 35 on the vault top section 20, the preferred embodiment includes a visual inspection mirror 49 (FIG. 5) as a visual aid for direct viewing the interior space 17, the primary tank 16 exterior surfaces, and the interior surfaces of the vault bottom 14 from a stationary position on the top of the vault top section 20.

[0081] With a combined artificial light source 49 a that moves with the mirror 49 b adjustments; a manual adjustment 49 c range from 0 degrees to 90 degrees available from the handle 49 d of the visual inspection mirror 49 assembly; and an extended handle 49 e; the use of the visual inspection mirror 49 can greatly increase and extend visual inspection capabilities within the interior spaces 17 of the assembled invention 10, without having to enter the space.

[0082] Depending on the degree of visual inspection and physical access capability desired in the design stage on any particular unit of the assembled invention 10, there are three means of viewing the interstitial space 17, the primary tank 16, and the interior of the vault bottom 14.

[0083] The first means is directed to viewing and physical access into at least two corners of the interstitial space 17 solely from the top of the vault top section 20 by means of at least two visual inspection port 35 assemblies positioned diagonally on opposite corners of the vault top 20; the second means is for visual and physical, confined space entry access into at least one corner of the secondary containment chamber 17 by means of a bolt down 51 a, gasketed 51 b, weathertight, manway 51 with removable cover 51 c, and in combination with at least one other visual inspection port 35, either of entry 51 or non-entry 35 design, and positioned diagonally on the opposite corner of the vault top 20. The third mans of viewing is by the introduction of a remote viewing device 52 into at least one visual inspection port 35 assembles, with a minimum of at least one more visual inspection port 35 assembly, either of entry 51 or non-entry 35 design, positioned diagonally on the opposite corner of the vault top 20 section. Incorporation and introduction of natural or artificial light means into the interstitial space 17 for enhanced viewing capability is included in the intended design.

[0084]FIGS. 2 and 4 show a top view of the a further embodiment in that visual inspection port 35 assemblies are positioned diagonally at all four corners of the vault top 20, and with corresponding visual inspection chambers 19 created inside each corner of the vault bottom 14 by means of the primary tank chambers 18, and directly below each of the visual inspection port assemblies 35; and sufficient in size to meet the visual inspection and physical access needs required.

[0085] Regardless of the specific configuration chosen, it is the intention of the current invention to be able to visually inspect, either directly or remotely, all four corners of the interstitial space 17, and all four sides of the primary tank 16, and the interior of the secondary containment structures 20 and 14; and further, to be able to physically remove liquids from the interior space 17 without having to remove the vault top section 20 from the vault bottom section 14, and/or without having to enter a confined space.

[0086] While ballistic protection, vehicular impact protection, and fire protection are primary concerns for the above ground embodiment, the below grade and at-grade designs must primarily address issues of downward load bearing pressures; lateral side wall pressures—both inward and outward; flotation of the inner and outer containers; water tight sealing of penetrations and joints; and visual inspection and maintenance in a confined space environment.

[0087]FIG. 6 shows a perspective view of a preferred below and at-grade system that incorporates the necessary designs to accommodate the issues above, as well as provide for visual and physical access into the space between the two containers without requiring entry into a confined space environment.

[0088] The vault bottom 14 and vault top 20 are joined in similar fashion to the above ground embodiment with a vault joint configuration 25 and a petroleum and water resistant elastomeric sealant material 28. The exterior vault bottom 14, however, is flat to provide for load bearing of the filled inner container 16, vault top 20, and any additional cover or concrete pad that may be installed over the assembled system 10.

[0089] Both the vault top 20 and the vault bottom 14 are preferably HS-20 bridge rated, which allows for a fully loaded tractor trailer to drive over the top of the assembled invention 10. The walls of the vault top 20 and vault bottom 14 are additionally reinforced to counteract lateral inward and outward pressures. Further, the vault bottom 14 provides additional anti-flotation by means of a reinforced apron 54 extending outward from the vault bottom. Once the assembled system 10 has been installed into an excavation, ready mix concrete is poured over and under the reinforced apron 54 to a depth of about 8″ in order to complete the concrete, anti-flotation apron design 54.

[0090] The exterior of the assembled system is coated with a polymer based coating 45 for enhanced resistance from ground and surface water. The vault joint 25 is further protected from underground elements by means of a butyl rubber wrap 52, or alternately, by means of a thermally sealed polymer 53 that joins the top 20 and bottom sections 14 of the vault into one unitized, weather tight assembly.

[0091] The interior of the vault bottom 14 provides for gravity movement of liquids to two corners by means of a channel 12 and sump 13 configuration. The interior of the vault top 20 and vault bottom 14 are sprayed with a two part epoxy coating 21, and a butyl rubber gasket material 24 is utilized between the primary tank feet 23 and the floor of the vault bottom 14.

[0092] The primary tank 16 is offset into one corner of the vault bottom 14 with a 5″ interstitial space on the two nearest sides between the primary tank 16 and the outer, reinforced precast vault top 20 and vault bottom 14 interior walls; and 18″ on the other two sides as shown in FIG. 6. The primary tank is sprayed with an epoxy coating 43 for protection against condensation and corrosion.

[0093] The primary tank 16 is tied down to the floor of the vault bottom by means of a tank tie down assembly 50 consisting of a series of tank mounted brackets 50 a and a corresponding series of cast-in, female threaded, inserts into the vault floor 50 b; threaded steel dowel rods 50 c and washers 50 d and nuts 50 e for securing the dowel rods 50 c to the tank mounted brackets 50 a on one end, with the other dowel rod end 50 c screwed into the cast-in floor inserts 50 b. This keeps the primary tank 16 from floating upward in the event of a flooding of the interior of the space 17 between the primary tank and the outer reinforced vault walls 20 and 14.

[0094] Advantageously, the tank tie down assembly design 50 permits for greater utilization of the interior space within the assembled invention 10, as the dowel rods 50 c are inserted into the floor of the vault bottom 14 prior to installing the primary tank 16, and the final assembly of the dowel rods 50 c to the tank mounted brackets 50 a is performed from the top of the tank 16 prior to assembly of the vault top 20. By not having to allow additional workspace for personnel entry to retrofit the tank tie down system 50 after the tank 16 and vault top 20 have been installed, a more efficient tank 16 placement within the vault cavity 17 is achieved

[0095] Although a variety tank shapes can be accommodated, the preferred shape of the primary tank 16 is rectangular with chamfers 18 on each of the four tank corners for enhanced visual inspection and physical access to the space between the two containers 17, and the wall surfaces of the two containers. The rectangular shape of the tank 16 provides the most efficient use of space 17 within the rectangular, outer reinforced vault top 20 and vault bottom 14 assembly.

[0096] By modifying the size of the tank chambers 18 and visual inspection ports 35 mounted on the vault top 20, physical entry access into the visual inspection chamber 19 created by the tank chamfer 18 and the interior walls of the outer, reinforced vault top 20 and vault bottom assemblies 14 is achieved as shown in FIG. 6 by means of ladders 55 installed into the diagonally opposite corners of the assembled vault 10.

[0097] Advantageously, diagonally top mounted visual inspection ports 35 on the other two corners of the vault top 20, provide for either direct or remote visual inspection and physical access into the interstitial space 17 without entering the confined space of the vault cavity 17. This feature of the invention promotes the visual inspection and regular maintenance of the system without the avoidance and deterrence normally associated with the regimen and hazards of having to enter a confined space area.

[0098] With the introduction of remote, digital, video equipment by means of the visual inspection port assemblies, scheduled snapshots or controlled video footage of the interstitial space 17 and the interior surfaces can be easily scheduled, logged, and maintained by computerized programming without the need for personnel entry unless an alarm is triggered by the presence of a liquid in the space 17.

[0099] The below grade and at-grade vaulted systems 10 provide for full time ventilation of the interstitial space 17 by means of a remotely mounted fan and piping system 56 (FIG. 9), as well as a fire suppression piping system 57 that connects each vault cavity 17 to an externally mounted standpipe (not shown ) for access by fire department personnel. An explosion proof lighting system (not shown) with a remote switch, is integral to the below grade and at-grade vaulted systems.

[0100] With the current invention, direct visual interior inspection of the primary vessel and secondary containment spaces and structures, whether above ground, below ground, or at-grade, is simply and easily achieved by removing the bolted down, gasketed, weather-tight, UL-2085 fire-rated covers of the visual inspection and physical access ports, strategically cast into two or more corners of the top of the secondary containment structure. Replacing the covers of the visual inspection and physical access ports after the desired inspection is as simple and easy as the initial cover removal process. Remote visual inspection, with optional periscopes or video camera equipment mounted in the visual inspection and physical access port assemblies, make the viewing process even more practical and useful, as the port covers do not need to be removed when this option is utilized, and physical entry is no longer essential to perform the visual inspection function.

[0101] With these functional design features, potential environmental and containment system maintenance problems can be readily anticipated and easily prevented by proactive visual inspections of the primary vessel and secondary containment spaces and structures. Remedies, at this stage, are relatively simple and inexpensive to resolve as they are limited to repair or replacement of the fully operational primary containment system before a fluid product release with potential adverse environmental impact can occur.

[0102] The current invention is based on the premise that, whether above ground, below grade, or at-grade, there is simply no substitute for being able to readily see with the human eye, the current condition of the primary vessel or interior secondary containment structure, interior components and the vessel and precast structure protective coatings designed to endure a typical 30-year service life. Additionally, the invention provides ample visual inspection and physical access into at least two of the four corners of the internal secondary containment space in order to absolutely verify the absence or presence of effluent and if required, to remove fluids from the interstitial space from a safe stationary position outside the containment system, without having to gain access to the interior by removal of a heavy precast secondary structure containment cover or top.

[0103] Modification and variation can be made to the disclosed embodiments without departing from the subject of the invention as defined by the following claims. 

What is claimed is:
 1. In a fluid containment system comprising: a. an outer container having a bottom wall and a plurality of side walls which project from the bottom wall to define an open cavity; b. an inner container within open cavity said inner container capable of holding fluids and spaced from the side walls of said other container; and c. a cover supported on said side walls to cover said cavity, the improvement which comprises said cover having at least one port to provide visual inspection and at least one physical access port to provide visual inspection and physical access into said cavity.
 2. The system of claim 1 , including means for providing natural or artificial light into said cavity.
 3. The system of claim 2 , wherein said natural light providing means is provided by removing the port covers; wherein said artificial light means is mounted on said port cover assemblies; or integral to the remote viewing device mounted onto the port assemblies.
 4. The system of claim 1 , wherein said viewing means comprises direct visual inspection by removing port covers; or remote visual inspection means of a visual inspection mirror, periscope; camera; and video camera.
 5. The system of claim 1 , wherein said space between said inner and outer containers is about 2-4 inches along the sides, top, and bottom; and about 8 inches to 36 inches directly under said port assemblies.
 6. The system claim 1 , wherein said cavity cover is removable.
 7. The system of claim 1 , wherein said outer container comprises reinforced concrete.
 8. The system of claim 1 , wherein said inner container comprises steel.
 9. The system of claim 1 , including sealing means between said cavity cover and said outer walls; and sealing means of tank penetrations through said cover.
 10. The system of claim 1 , which is an above ground liquid storage system.
 11. The system of claim 1 , which is a below grade liquid storage system.
 12. The system of claim 1 , which is an at-grade liquid storage system.
 13. The system of claim 1 , where said cavity cover includes vent means and means for access into said inner container.
 14. The system of claim 1 , including a secondary containment coating on the inner surface of said side walls.
 15. The system of claim 1 , including an interior channel and sump configuration in the bottom wall of the container that moves liquids by gravity to at least two corners and directly below the port assemblies.
 16. The system of claim 1 , where said container includes chamfered corners for enhanced visual and physical access into the space between the two containers.
 17. The system of claim 1 , where said ports are fire rated at 2000 degrees for two hours.
 18. The system of claim 1 , where said inner container is securely tied down to the bottom wall of the outer container.
 19. The system of claim 1 , including an outer anti-flotation apron of reinforced concrete.
 20. The system of claim 1 , wherein said viewing port comprises. 